Tool set assembly for powder compacting press and the like

ABSTRACT

A UNITARY TOOL SET ASSEMBLY FOR MOUNTING IN A POWDER COMPACTING PRESS, HAVING A DIE PLATE PROVIDED WITH ONE OR A PLURALITY OF DIE CAVITIES AND TO WHICH IS MOUNTED A HOUSING EXTENDING BELOW THE DIE PLATE AND CONTAINING ONE OR A PLURALITY OF PUNCHES INDIVIDUALLY DISPOSED IN EACH DIE CAVITY. A STATIONARY CORE ROD IS DISPOSED IN EACH PUNCH AND THE PUNCHES ARE COLLECTIVELY ACTUATED FOR RECIPROCATION BY A COMMON PUNCH HOLDER TO WHICH THEY ARE   RIDIGLY AFFIXED DURING INITIAL ASSEMBLY OF THE TOOL SET IN AN IMPROVED MANNER SUCH AS TO MAINTAIN THEIR ACCURATE ALIGNMENT RELATIVE TO THE DIE CAVITIES AND THE CORE RODS.

Nov. 23, 1971 G. D. DE TRoYER 3,621,534

TOOL SET ASSEMBLY FOR POWDER COMPACTING PRESS AND TINE] LIKE INVENTORGEORGES D' DETROYER ATTORNEYS Nov. 23, 1971 G. D. DE TROYER 3,521,534

TOOL SET ASSEMBLY FOR POWDER COMPACTING PRESS AND 'THE LIKE Filed sept.29, 1999 2 Smets-sheet z 4M 254 g/d 4M INVENTOR FIG- 4G y GEORGES o.DETROYER ATTDRNEYS United States Patent Ofce 3,621,534 TOOL SET ASSEMBLYFOR POWDER COMPACT- lNG PRESS AND THE LIKE Georges D. De Troyer,Detroit, Mich., assignor to Wolverine Pentronix, Inc., Lincoln Park,Mich. Filed Sept. 29, 1969, Ser. No. 861,672 lut. Cl. B30b 11/02 U.S.Cl. 18--165 21 Claims ABSTRACT OF THE DISCLOSURE A unitary tool setassembly for mounting in a powder compacting press, having a die plateprovided with one or a plurality of die cavities and to which is mounteda housing extending below the die plate and containing one or aplurality of punches individually disposed in each die cavity. Astationary core rod is disposed in each punch and the punches arecollectively actuated for reciprocation by a common punch holder towhich they are rigidly afxed during initial assembly of the tool set inan improved manner such as to maintain their accurate alignment relativeto the die cavities and the core rods.

CROSS REFERENCE TO RELATED APPLICATIONS The present application isrelated to applications Ser. No. 767,648, now Pat. No. 3,561,056 led onOct. 15, 1969 in the name of Joseph E. Smith, Jr. and Georges D. DeTroyer, entitled Tool Set for Powder Compacting Press, and Ser. No.794,196, now Patent No. 3,574,892 filed Jan. 27, 1969 in the name ofJoseph E. Smith and entitled Powder Compacting Press. The presentapplication lis also related to issued Patents Nos. 3,328,840,3,328,842, 3,344,214, 3,414,940 and 3,415,142.

BACKGROUND OF THE INVENTION (I) Field of the invention The presentinvention relates to the eld of tool set assemblies for powdercompacting presses and the like, although it will be appreciated thatthe particular punch and punch holder construction of the invention hasalso substantial usefulness in other similar arrangements where aprecise alignment of members reciprocating relative to each other is ofimportance.

(Il) Description of the prior art Powder compacting presses and the likemachines utilize one or several punch members each disposed at thebottom of and displaceable in a cavity which has been filled with loosepowder material to be compacted to an appropriate shape, generally inthe shape of a cylinder, disk or toroid. The loose powder material iscompacted between the end of the punch member and the end of acounter-punch or, .alternately as disclosed in the hereinbefore referredto patents and applications, between the end of the punch member and ananvil arranged to bedisplaceable over the die cavity for closing theopen end thereof. Each punch may be individually actuated by anactuating mechanism or the punches may be disposed in a cluster and heldby a common punch holder so as to be simultaneously and jointlydisplaceable, each punch member being disposed within an individual diecavity. The common punch holder holding a plurality of punches has, asalso disclosed in the hereinbefore mentioned patents and applications, apunch holding head provided with a circumferential groove adapted toaccept an enlarged diameter end portion of the punch, the projectingbody portion of the punch being disposed within a radial slot extendingfrom the top surface of the punch holding head of 3,621,534 PatentedNov.. 23, 1971 the holder for intersection with the circumferentialgroove.

The working end of the punch is adapted to slidably engage the innerbore of a die bushing which defines the die cavity and both the punchmember and the die bushing are preferably made of an ultra hardmaterial, for example a cemented carbide of a metal such as tungsten,titanium or the like, to insure appropriate rigidity, sturdiness,resistance to compression, and resistance to wear of the workingportions of the punch and die.

The aforementioned patents and applications show examples ofconstruction best adapted to provide punches for compacting magneticmemory cores from ferrite powder and the like. A magnetic memory core isgenerally in the form of a toroid, a few thousandths of an inch indiameter, having a central aperture for the threading therethrough ofwires when a plurality of nished sintered cores are disposed in anappropriate frame so as to form a magnetic memory plane or the like.Magnetic memory cores we're formerly of a substantial size, of the orderof mils in diameter, but the size has been continuously and consistentlydecreased over the years following a trend towards miniaturization andfaster response of magnetic core memory stacks. Magnetic cores of 25, 20and 18 mils are currently being manufactured, and the trend is stilltoward further miniaturization aiming at magnetic core sizes of only 16,12 and even 8 mils or less. iIt is obvious that such a trend towardminiaturization of magnetic cores renders more critical the precisionwith which ferrite compacting presses and tooling must be built. Hollowpunches having a precise O.D. dimension of the order of ..012, .008, or.006 in., with a wall thickness from .001 to .005 in., and made of anultra hard material, such as a carbide or the like, require precisemanufacturing apparatus and techniques, and delicate and preciseinstrumentation for checking the nished cores. The precision of fitbetween the punch outer diameter and the die bushing inner diameter mustbe held within .0005 in., and such a precision must be maintained overthe life of the punch so as to provide constant density and dimensionalprecision in the pressed cores.

A further complication in manufacturing punches for ferrite compactingoperations is due to the substantial length of the punch which resultsin a slender part which may easily break due to the brittleness of thematerial with which it is made, when subjected to uneven or bendingstresses. Consequently, the punches must be precisely mounted in anappropriate holder, and high precision is required in the fittingbetween the holder and the punch supporting means therein. Concentricityof the longitudinal bore through the punch and high precision in thedimension of the inner diameter of each bore, permitting passagetherethrough of the core rod, are also essential.

The prior art has attempted to solve the many problems presented by theaforementioned requirement for satisfactory punch construction forferrite compacting machines, but without too much `success to date.

As disclosed, for example, in the aforementioned patents andapplications, a plurality of identical punch assemblies are mounted onthe end of a common holder and are disposed preferably in a circulararrangement on the enlarged end of the holder for reciprocation inunison by such holder driven by an appropriate ram forming part of thepress mechanism. A portion of the end of each punch is engagedcontinuously in the bore of a die bushing supported in an appropriatedie plate on the press and forming the die cavity. The space in the diecavity above each punch end is filled with a predetermined amount ofpowder material by appropriate filling means, and an upper compactingmember or anvil is disposed over the open end of the die cavity orcavities and all the punches are displaced in unison by their commonpunch holder so as to compress the powder material against the face ofthe anvil with a predetermined pressure, which may be as high as severaltons. The anvil is removed from the die cavities and the compacted partsare subsequently ejected from the die cavities by further upward motionof the punches and appropriate pickup means to pick up the compactedparts.

The most important disadvantage of the prior art construction is due tothe fact that under repeated pounding in the course of compacting coresor the like, which, as previously mentioned, is effected at pressures ashigh as several tons, the punches, since they are permitted to floatradially, under the repeated pounding cause a misalignment with theresult that the original precise positioning of the end of the punchengaged with the powder material is not only gradually lost but, inaddition, the repeated impacting forces transmitted through the punchcauses considerable wear on the end faces of the punches and theinternal surfaces of the die bushings.

Although this conventional floating punch arrangement on the punchholder as exemplified, for instance, in U.S. Pat. No. 3,414,940 providesduring assembly a desirable self-aligning feature for the punches andassociated core rods relative to the bores of the die bushings whichdefine the spaced die cavities, the floating arrangement of the puncheson the punch holder may present some disadvantage Which is'particularlypronounced in relatively small tool sets for the compacting ofminute-size tablets, memory cores or the like, which require greatdimensional accuracy and consistency within any particular productionrun.

Additionally, in a conventional assembly, the die bushings are usuallypress-fitted in their respective die plate apertures so as to besubstantially rigid therein. However, even in the most tightly fittedassemblies, microscopic spaces remain between the adjoining surfaces ofthe fitted parts, which, due to the large forces during compactingoperation, eventually cause the die bushings to loosen and to movewithin their apertures resulting in the production of dimensionallyinaccurate compacted articles. This condition, together with therelative radial floatability of the punches causes extensive wear sothat the complete tool set has to be frequently renovated. In severecases of punch misalignment and die bushing movement, fretting takesplace and eventually the punches may break.

SUMMARY OF THE INVENTION Accordingly, the present invention provides animproved construction and improved means to precisely align in assemblyand thereafter rigidly maintain the punch or punches on the punch holderin accurate central relation relative to the die cavities defined by thebores of the die bushings disposed in the die plate. Similarly, the diebushings are rigidly fitted within their respective apertures in the dieplate such that they are prevented from loosening and subsequentmovement within their apertures even when subjected to prolonged highcompacting forces. Although, the die bushings and punches are rigidlyretained, disassembly for renovation of the tool set is possible, afterwhich the parts can again be rigidly reassembled.

The advantages and novel features of the present improved tool set willbe more clearly apparent by reference to the following detaileddescription of several examples of preferred embodiments.

DESCRIPTION OF THE DRAWINGS The appended drawings illustrate theexemplary forms of the preferred embodiments in which:

FIG. 1 is a fragmentary top plan view of one example of a tool setincluding an improved punch and die assembly according to the presentinvention;

FIG. 2 is an enlarged fragmentary cross section through 4 the centerportion of the tool set shown in FIG. 1 as seen along line 2-2;

FIG. 3 is a fragmentary top plan view of another eX- ample of a tool setincluding an improved alternate punch and die assembly according to thepresent invention;

FIG. 4 is a transverse cross section through the center of the tool setshown in FIG. 3 as seen along line 3-3;

FIG. 4a is an enlarged fragmentary section of the center portion of thetool set shown in FIG. 4;

FIG. 5 is a cross section through the tool housing and punch holderassembly of the tool set shown in FIG. 4 as seen along line 5-5;

FIG. 6 is an enlarged fragmentary cross section of two press-fittedadjoining surfaces of a die aperture and die bushing, for example, asseen under a microscope to more clearly illustrate the mechanics of theimproved assembly method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1 andwith particular reference to FIG. 2, there is illustrated in top planview and in cross section, a fragmentary portion of an improved tool setassembly constructed in accordance with the present invention. Theimproved tool set assembly 10 comprises a die plate 12, having a smoothtop surface 13 and which is provided with a plurality of equally spacedcircularly arranged apertures 14 each receiving a die bushing 15lprovided each with an axial through bore 16 which define a die cavity.

In assembly, the die plate 12 will be mounted in the press or similarmachine by means of the provision of bolt mounting apertures 17 providedinthe dieplate. A housing 18 is secured to the underside of the dieplate 12 by means of a radial ange 19 adapted to receive machine screws20 for threading engagement within apertures 11 provided in the dieplate 12 to thereby secure the housing 18 to the die plate. The housing18 is provided with an axial bore 21 which at the upper end is formedinto a counter-bore 22 of enlarged diameter. The axial bore 21 of thehousing 18 is centrally aligned with the center of the circle on whichthe die apertures 14 are disposed, and is adapted to receive the pushrod 23 of the punch holder 24, which at its upper end, Within thecounter-bore 22, is provided with an enlarged head portion 25 of adiameter substantially corresponding to the diameter of the counter-bore22. The punch holder 24 is reciprocable within the axial bore 21 and isadapted to support a plurality of punch members 216y supported on theenlarged head portion 25. The punch members 26 are each constructed toprovide a cylindrical shank portion 27 adapted for extension into thedie cavities 16, as shown in FIG. 2, and their lower ends are providedeach with an enlarged head portion 28 adapted to rest on the top surfaceof the enlarged head portion 25 of the punch holder 24. The punchmembers 26 are held on the enlarged head portion 25 of the punch holder24 by means of an inner spacer ring 29 disposed centrally between thehead portions 28 of the punch members 26', an outer spacer ring 30extending radially around the enlarged head portions 28 of the punchmembers and a clamping plate 31 which, in assembly, is tightly securedby a bolt 3-2 threaded into the punch holder 24 centrally thereof andhaving a head 33 adapted to extend into a through bore 34 provided inthe die plate 12. It Iwill be noted that the thickness of the innerspacer ring 29 and outer spacer ring 30 corresponds to the 'thickness ofthe enlarged head portions 28 of the punch members to permit clampingplate 31, when tightened by means of the bolt 32, to exert an equalpressure on all three members and thereby rigidly secure the punchmembers to the head portion 25 of the punch holder 24. The inner spacerring 29 and the clamping plate 31 are aligned in assembly relative toeach other by means of dowel pins 35 extending through both members andinto the enlarged head portion 25 of the punch holder 24. A radial space36 is provided between the enlarged head portions 28 and the innerspacer ring 29 and Outer spacer ring 30, respectively, and the clampingplate 31 is provided with a plurality of equally spaced apertures 37through which the cylindrical shank portions 27 of the punch members 26extend for insertion into the die cavities 16. It will be noted that theplate apertures 37 are of slightly larger diameter than the shankportions 27 of the punch members 26, which, in cooperation with theradial space 36, provides a self-aligning means for the punch members 26relative to the die cavities 16 during assembly and prior to tighteningof the bolt 32.

yCertain compacted articles are required to be provided with aperturesand for this purpose core rods 38 are provided for extension axiallythrough the punch members 26. The core rods extend out of the headportions of the punch members through aligned apertures 39 provided inthe enlarged head portion 25 of the punch holder 24 and through alignedbores 40 provided in the housing 18 parallel to the axial bore 21. Thelower ends of the core rods ha've enlarged shank portions 41 by means ofwhich the core rods are adjustably secured to the housing 18 byprovision of individual set screws 42 extending through the wall of thehousing 18 to maintain the core rods 38 in stationary position relativeto the reciprocating punch members 26.

Assembly of the improved punch holder structure 24 is as follows: thepunch holder 24, having the dowel pins 35 attached to the head portion25, is inserted from the top of the housing 18 so that the push rod 23extends through the axial bore 21 with the enlarged head portion 25being retained within the counter-bore 22 of the housing. The innerspacer ring 29 is then placed centrally on the head portion 25 over thedowel pins 35 and the punch members 26 are arranged around the innerspacer ring 29, whereafter the outer spacer ring 30 is placed around thepunch members 26. The shank portions 27 of the punch members 26 are thenplaced in alignment with their respective apertures 37 of the clampingplate 31, which is then placed over the punch members for abutment uponthe top surfaces of the inner spacer ring 29, outer spacer ring 30 andenlarged head portions 28 of the punch members. The clamping plate 31and the inner ring 29 are aligned relative to the head portion 25 of thepunch holder 'by means of the locating dowel pins 35. The bolt 32 isthen inserted through the aligned central apertures provided in theclamping plate 31 and the inner spacer ring 29 and loosely screwed intothe punch holder 24. The shank portions 27 of the punch members 26 arethen aligned relative to the die cavities 16 by means of their abilityto float radially within the respective top plate apertures 37 and theradial space 36 provided between the inner and outer spacer rings 29 and30. After correct central alignment of the shank portions 27 with thedie cavities 16 and threading of the shank portions 27 into therespective die cavities, the bolt 32 is tightened by means of insertionof a tool (not shown) through the central apertures 34 in the die plate12 so as to rigidly clamp the assembly in the aligned position, whichthereafter will be securely maintained during operation of the tool set.

The die bushings are rigidly retained within their respective die plateapertures 14 by the use of a quick setting bonding compound, as will bemore in detail described in connection with the preferred embodimentillustrated in FIGS. 3 to 5, and -which is a particular feature of thepresent invention. By this method, the die bushings 15 are rigidlyretained within their apertures and prevented against radial and axialmovement therein during the compacting operation.

As further seen from FIG. l, the die plate 12 may be additionallyprovided with another set of apertures 44 corresponding in number to thedie bushing apertures 14 and which are preferably arranged in the samepattern. Apertures 44 are discharge `apertures to dispose of the finishcompacted parts as is known from the aforementioned U.S. patents orpatent applications.

With reference to FIGS. 3-5 in the drawings, a preferred modication ofan improved tool set 10a of the present invention comprises a modifieddie plate 12a having a relatively smooth top surface 13 which iscentrally provided with a iirst group of a plurality of apertures 14preferably arranged in a circle as best shown in FIG. 3. The die plateis further provided with a second group of apertures 44 corresponding innumber to the apertures 14 which are arranged in the same circularpattern as apertures 14 and positioned closely adjacent thereto.

The first group of apertures 14 are each provided with a cylindrical diebushing 15, which each have an axial bore 16 deiining a die cavity. Thesecond group of apertures 44 dene discharge apertures for the nishedcornpacted parts and normally are connected by conduits or the like toseparate containers (not shown). In normal installation, as disclosed inthe aforementioned U.S. patents and applications, the die plate 12a issecured in the press by means of bolt apertures 17 and means movableabove the surface 13 of the die plate 12a are provided (not shown) asdisclosed in the related references to iill the die cavity or cavities16 with powdered material for compacting of the powdered materialtherein.

With particular reference to FIGS. 4 and 4a, a housing 18a, forming asubstantially cylindrical body, is attached to the underside 45 of thedie plate 12a by means of a radial ilange 19a provided with bolts 20threadingly retained in threaded apertures 11 in the die plate 12a. Thehousing 18a has an axially centered through bore 21a for the slidingextension therein of the push rod 23a of a punch holder 24a. The axialthrough bore 21a is axially aligned with the center of the die plate 12awhich forms the center of the circle of the die cavities 16 and theupper end of the axial bore 21a forms a cylindrical counter-bore 22a ofsubstantially larger diameter than that of the axial bore 21a. The pushrod 23a, which is reciprocable within the axial through bore 21a, isprovided with a radially enlarged head portion 70 disposed within thecounter-bore 22a of the housing for reciprocation therein. As mostclearly seen in FIG. 4a, the head portion 70 of the punch holder 24acomprises a radial ange 72 having an external diameter substantiallycorresponding to the internal diameter of the counterbore 22a. The uppersurface of the radial flange 72 is provided with an axially extendingboss portion 74 adapted to extend into a corresponding recess 76provided in the underside 45 of the die plate 12a. The radial ange 72 ofthe head portion 70 is provided at two circumferentially oppositepositions with semi-circular recesses 78 (FIG. 5 which are adapted, inassembly, to be engaged by a pair of dowel pins 80 each extendingthrough appropriately aligned apertures 82 in the die plate 12a and intoblind apertures 84 in the bottom 69 of the counter-bore 22a of thehousing 18a to thereby axially align the head portion and preventrotation of the same during reciprocation of the punch holder 24a'within the housing 18a. The head portion 70 of the punch hoder 24a isfurther provided with a plurality of radially disposed equally angularlypositioned bores 86 corresponding in number to the number of diecavities 16 in the die plate, and in axial alignment therewith. Theboxes 86, which are provided at their lower end with counter-bores 87,extend through both the lange portion 72 and the boss portion 74 of thehead portion and are adapted to receive each a punch member 26a rigidlysecured therein, as will be explained.4

The punch members 26a are each composed of a cylindrical body having asmoothly nished outer surface and a diameter substantially correspondingto the internal diameter of the die cavities 16 into which they extendand they are each provided with :a central axial through bore forextension of a core rod 318 therethrough in axial sliding engagementrelative therewith. Each of the core rods 38 extends downwardly out ofthe head portion parallel to the push rod 23a and into longitudinalbores 40a provided in the wall portion of the housing 18a, in which theenlarged diameter shank portions 41a of the core rods extend for rigidsecurement of each of the core rods against longitudinal movement bymeans of appropriately radially positioned set screws 42 (FIG. 4), orthe like, extending radially through the wall portion of the housing18a.

Preferably, but not exclusively, a retaining plate 100 is providedaround the upper end of the push rod 23a between the underside of thehead portion 70 and the bottom 69 of the counterbore 22a in the housing18a, which is secured to the head portion 70 by means of screws 102, asseen in FIG. 5, to be reciprocably movable therewith. As further shownin FIG. 5, the circumferential portions of the retaining plate 100opposite the dowel pins 80 are cut away along a chord line 104 in orderto clear the dowel pins 80. The retaining plate 100 provides a backupand abutment member for the punches 26a. In certain instances, theretaining plate 100 can be dispensed with completely. The core rods 38extend through the retaining plate 100 by means of suitably radiallyspaced apertures 106.

Generally, in the initial assembly of the tool set 10a, the die plate12a is placed with its top surface 13 upon a smooth planar assemblysurface (not shown) whereupon one die bushing 15 is inserted in each ofthe apertures 14 for abutment upon the planar assembly surface so as tobe flush with the die plate surface 13. Each of the punches 26a is theninserted within one die bushing 15 and the punch holder 24a is thenplaced over the punches such that their end will be substantially flushwith the underside 71 of the head portion 70 of the punch holder.Thereafter, the retaining plate 100, when used, is moved over the pushrod 23a and secured to the underside 71 of the head portion 70 by meansof the screws 102. The dowel pins 80 are then press-fitted in theirapertures 82 in the die plate such that they extend through thesemi-circular recesses 78 in the radial flange 72 of the head portion 70and past the lateral chord surfaces 104 of the retaining plate 100.

The core rods 38 are then threaded through the apertures 106 in theretaining plate 100 into the correspondingly aligned axial bores of thepunches 26a to drop downwardly upon the assembly plate. The housing 18ais positioned upside down and pushed over the push rod 23a. The housing18a is radially positioned to permit the core rod shanks 41a to enterthe respective bores 41a, and the dowel pins 80 to enter the blind bores84 in the housing to thereby radially locate the housing relative to thedie plate 17a. The housing is then fastened to the underside of the dieplate by means of the bolts and the core rods 38 are secured to bestationary with the housing 18a by means of tightening of the set screws42 to thereby complete the assembly.

In accordance with the present invention, the improvement consists inrigidly securing the die bushings 15 and punches 26a in their respectivesupporting apertures 14 and 86 after assembly of the parts, so that theyremain at all times rigid and properly aligned relative to each other.This is accomplished herein by securing the die bushings 15 and punches26a in their respective apertures 14 in the die plate 12 or 12a and 86in the head portion 70 of the punch holder 24a by means of a commercialquick-setting bonding compound, such as an anaerobic adhesive. As anexemplary example, one of such bonding compounds is known and marketedunder the name of .Loctite manufactured by the Loctite Corporation,Newington, Conn. This compound, particularly useful in the bonding ofcylindrical parts, is an anaerobic adhesive having an unusually highshear strength exceeding that of conventionally press-litted parts forup to five times. The Loctite retaining compound is fast curing and hasexcellent heat and solvent resistance characteristics, as well asproviding a high shear strength between the adjoining interfaces.

The surfaces of internally and externally machined cylindrical parts arenever really smooth, but have a certain roughness, the degree of whichdepends on the type of machining. When viewed under a microscope, themachined surfaces show valleys and peaks of microscopic dimensions,which, however, when two of these surfaces are brought close togethersuch as in press-fitting a cylindrical part Within a cylindrical bore,cause microscopic air spaces to appear between the interfaces since thesurfaces actually touch each other only at the high spots or peakspermitting the valleys of the surfaces to form air spaces or pockets.These air spaces or pockets are the source of serious problems, such asloosening under vibrating or impact forces, leakage or corrosion. Thefunction of the anaerobic adhesive is to ll these air apaces betweenadjoining, preferably tightly tted surfaces with a self-hardeningcompound which, when hardened, rigidly joins or bonds the surfacestogether.

Accordingly, and with particular reference to FIGS. 2 and 4a, duringassembly of the die bushings 15, the internal surfaces of the dieapertures 14 are provided with a few drops of an anaerobic adhesiveindicated at 108. The surfaces are machined such as to provide aninterference t. The die bushings are then pressed into their aperturesand properly axially positioned relative to the surface of the dieplate. This is done on a heated assembly plate which is warmed tobetween and 100 F. to facilitate curing of the adhesive.

Similarly, and with reference to FIG. 4a, the punch members 26a areinserted in their respective apertures 86 in the head portion 70 of thepunch holder 24a and after having been axially positioned within the diebushings 15 a few drops of Loctite compound is applied to thecounter-bores 87 of the apertures 86 and, due to the characteristic ofthe Loctite compound, the compound seeps along the interfaces betweenthe punch 26a and the apertures 86. The characteristic of the anaerobicadhesive is such that it remains liquid in free state, that is, underfree flow conditions, however, if placed under restrictive owconditions, such as exist in a microscopic clearance occuring betweenthe adjoining interfaces of two tightly tted members, it becomeshardened to provide a solid bond between the surfaces. As can best beseen in FIG. 6, the anaerobic adhesive 108 settles in and fills the airspaces or pockets formed by the valleys of the adjoining surfaces andthus tightly bonding the surfaces together along the peaks 112 formed onthe machined surfaces, thereby preventing relative longitudinal movementbetween these surfaces due to the high shear strength of the adhesiveeven if subjected at prolonged intervals to the relatively highcompacting forces during operation of the press.

If it becomes necessary to renovate either tool set 10 or 10a after acertain time of operation, the die bushings 15 are pushed outwardly oftheir respective apertures 14 by means of an appropriate tool, as forinstance an arbor press, having a force capacity exceeding the shearstrength limit of the particular anaerobic adhesive compound. The diebushings are pushed out a small distance beyond the top surface 13 ofthe die plate to extend an amount of about two to five-thousandths(.002-.005) of an inch. The core rods 38 are loosened and extended adistance to be level with the top surface of the die bushings and thensecured again to the housing 18 or 18a. The punches 26a are movedupwardly in the die bushings a lesser amount than the bushings toslightly extend beyond the top surface 13 of the die. plate an amount ofapproximately one or two thousandths of an inch (.001-.002). The diebushings 15 and punches 26a then remain solidly locked in this positiononce the force is removed therefrom due to the quick-settingcharacteristic of the anaerobic adhesive between their interfaces. Thetool set is now ready for renovation by grinding on a surface grinder,or the like, by which, simultaneously, all of the worn edges of the diebushings, punches and core rods are ground off until they are liush withthe surface of the die plate. Thereafter, the tool set is being lappedby movement of the top surface 13 of the die plate across an appropriatelapping plate, thereby reestablishing the necessary sharp edges on thedie bushings, punches and core rods. The tool set is then again readyfor use.

It will be appreciated that the tool set in itself also convenientlyprovides the grinding fixtures, thereby eliminating the tedious task andcost of disassembly of the tool set and reassembly and alignment of theindividual parts in a properly designed grinding xture.

It will be appreciated from the foregoing description and in referenceto the drawings that the improved construction and assembly method ofthe present invention provides an accurately aligned rigid tool setassembly providing precisely positioned punches and die bushings,although retaining fully self-aligning capability during assembly and inwhich all of the working parts will be rigidly locked in place afterassembly and alignment and maintained in the once assembled position forany length of time, or until the tool set has to be renovated, to makecompacted articles of a repeating, consistently high quality. This is ofparticular importance in the production of very small compacted articlesof micro-size, such as memory cores, which do not permit any dimensionalinconsistency, however small.

Furthermore, it can be seen that a more precise dimensional control ofthe finished articles is obtained with the improved tool set assemblybecause of the elimination of any relative movement between the workingparts.

Although only two preferred embodiments of the present invention areherein described, it will be apparent to anyone skilled in the art towhich the invention pertains that various changes and modifications maybe made therein without departing from the spirit of the invention asexpressed in the scope of the appended claims.

I claim:

1. A tool set for making articles compacted of powder material, saidtool set comprising:

a die plate adapted to be mounted in an appropriate aperture in amachine base;

at least one die cavity in said die plate defined by a die bushing ttedin an aperture in said die plate and having a bore open at lboth ends;

a punch having an end engaged in one end of said bore and reciprocabletherewithin;

a punch holder;

a housing secured to the underside of said die plate, having an axialthrough bore communicating with said die cavity in said die bushing;

means to rigidly secure said die bushing in said aperture in said dieplate; and

means to rigidly secure said punch to said punch holder in axiallycentered relationship relative to the bore of said die bushing so as toprevent any radial movement and misalignment relative to each other,said means being arranged to permit said punch to axially align itselfrelative to said bore during assembly of said tool set.

2. The tool set as dened in claim l, in which said punch holder has anenlarged head portion, said punch being radially and axially immovablysecured to said enlarged head portion in alignment with said die cavity.

3. The tool set as defined in claim 1, in which said means to securesaid die bushing in said aperture in said die plate comprises ahardenable bonding agent provided between the outer surface of said diebushing and the inner surface of said aperture in said die plate.

4. A unitary tool set for making articles compacted of powderedmaterial, said tool set comprising:

a die plate adapted to be mounted in a machine base;

a plurality of die cavities in said die plate comprising l0 cylindricalbores open at both ends, each of said die 'cavities being formed by theaxial bore of a die bushing fitted in an appropriate aperture providedin the d1e plate and rigidly secured within said aperture by means of abonding agent;

a plurality of punches each having one end slidingly engaged in one ofeach of said die cavities for reciprocation therein;

a punch holder for the support of said plurality of punches, said punchholder having an enlarged head portlon;

a housing secured to the underside of said die plate, having an axialthrough bore communicating with said die cavities in said die bushings;and

holding means for securing said punches to said er1- larged head, saidholding means being arranged to permit each of said punches to eachalign itself in the axial bore of each of said die bushings duringassembly of said tool set and to secure each of said punches rigidlyretained longitudinally and radially on said head portion in axiallycentered position relative to each of said die cavities prior tomounting of said tool set in said machine base.

5. The unitary tool set as defined in claim 4, in which said punches arerigidly retained within apertures in said enlarged head of said punchholder by means of a hardenable bonding agent preventing radial andlongitudinal sliding movement of said punches within said enlarged headapertures after hardening of said bonding agent.

6. The unitary tool set as defined in claim 5, in which said hardenablebonding agent is a liquid adhesive adapted to fill the intersticescreated by the surface roughness of the adjoining interfaces of theouter surface of said punches and the inner surface of said apertures insaid enlarged head.

7. The unitary tool set as defined in claim 5 in which said bondingagent for securing the die bushings in the apertures in the die plate isa liquid adhesive adapted to fill the interstices created by the surfaceroughness of the adjoining interfaces of the outer surface of said dieblshings and inner surface of said apertures in said die p ate.

8. tool set assembly for a powder compacting press comprlsing:

a `die plate having a working surface, said die plate being providedwith at least one aperture;

a die bushing having an axial through bore defining a die cavity andrigidly secured in said aperture in said die plate by means effectivelypreventing longitudinal and radial movement of said die bushing withinsaid aperture in said die plate during operation of said compactingpress;

a housing secured to the underside of said die plate, having an axialthrough bore communicating with said die cavity in said die bushing;

said through bore in said housing extending into an enlarged diametercounter-bore at the upper end of said housing adjacent the underside ofsaid die plate;

a punch holder reciprocably supported within said through bore of saidhousing and having an enlarged head portion disposed within the enlargeddiameter counter-bore in said housing;

a punch member having an end attached to said head portion forreciprocation therewith and another end adapted to extend in axiallyaligned relationship with said die cavity in said die bushing; and

means to rigidly secure the first end of said punch member to said headportion of the punch holder to prevent misalignment of the other end ofsaid punch member relative to said die cavity in said die bushing priorto mounting said tool set assembly to said powder compacting press.

9. The tool set assembly as defined in claim 8 in which said meansrigidly securing the die bushing in the aperture in said die platecomprises a curable synthetic ad- 1 1 hesive adapted to provide a securebond between the interfaces of said die bushing and said die plateaperture.

10. The tool set assembly as defined in claim 9, in which said curableadhesive is a liquid capable of hardening in restricted spaceconfinement as between the interfaces of said die bushing and saidaperture in said die plate.

11. The unitary tool set as defined in claim 8, wherein the enlargedhead portion of said punch holder is provided with an aperture axiallyaligned with said die cavity in which the first mentioned end of saidpunch member is engaged and rigidly retained by means of a curablesynthetic adhesive preventing radial and longitudinal movement of saidpunch member relative to said punch holder after hardening of saidadhesive.

12. The tool set assembly as delined in claim 11 in which said enlargedhead portion of said punch holder is of a predetermined thickness tothereby establish the extent of movement of the second mentioned end ofthe punch member within the die cavity in said die bushing.

13. The tool set assembly as defined in claim 12, further provided witha spacer plate mounted between said enlarged head portion of said punchholder and the top of said counter-bore of said housing to therebyselectively limit the extent of movement of the second mentioned end ofsaid punch member within the die cavity in said die bushing according tothe thickness of said spacer plate.

14. The tool set as defined in claim 2, in which said punch is providedwith an enlarged head portion engaged with the end face of the enlargedhead portion of said punch holder and is secured thereto by means of aclamping plate provided with an aperture for passage therethrough of thepunch end engaged in the bore of said die cavity with the enlarged headportion of each punch disposed between said clamping plate and the endface of the enlarged end portion of said punch holder, and threadededclamping boltmeans for drawing said clamping plate` toward said end facefor securely and rigidly holding said punch enlarged end portionrelative to said punch holder.

1S. The tool set as dened in claim 14, further comprising spacer meansdisposed between said clamping plate and said end face of said punchholder.

16. The tool setas defined in claim 1, wherein said punch holder isprovided with an aperture in which the other end of said punch isengaged, said other end of said punch being rigidly retained within saidpunch holder aperture by means of a hardenable bonding agent pre- 12venting radial and longitudinal movement of said punch Vrelative to saidpunch holder after hardening of said bonding agent.

17. The unitary tool set as dened in claim 4, in which each of saidpunches is provided with an enlarged head portion engaged with the endface of the enlarged head portion of said punch holder and in which saidholding means comprises a clamping plate provided with an aperture forpassage therethrough of the punch end slidingly engaged in said diecavity with theenlarged head portion of said punch holder, and threadedclamping bolt means for drawing said clamping plate toward said end facefor securely and rigidly holding said punch enlarged end portionrelative to said punch holder.

18. The unitary tool set as defined in claim 17, further comprisingspacer means disposed 'between said clamping plate and said end face ofsaid punch holder. 19. The unitary tool set as defined in claim 8, inwhich the lirst end of said punches is provided with an enlarged headportion engaged with the end face of the enlarged head portion of saidpunch holder, and further comprising a clamping plate provided with anaperture for passage therethrough of the punch other end with the enllarged head portion of said punch disposed between said clamping plateand the end face of the enlarged end portion of said punch holder, andthreaded clamping bolt means for drawingsaid clamping plate toward saidend face for securely and rigidly holding said punch enlarged endportion relative to said punch holder.

20. The unitary tool set as defined in claim 19, further comprisingspacer means disposed between said clamping plate and said end face ofsaid punch holder.

21. The unitary tool set as defined in claim 11, wherein said curableadhesive is a liquid adhesive adapted to fill the interstices created bythe surface roughness of the adjoining interfaces of the outer surfaceof said punch member and inner surfaces of said aperture in the headportion of said punch holder.

References Cited UNITED STATES PATENTS 3,414,940 12/1968 Vinson18--l6.5X 3,499,183 3/1970 Parsons 308-237 X ROBERT L. SPICER, J R.,Primary Examiner PEN-11H* UNHED STATES PATENT @NICE CERTIFICATE FCORRECTION Patent No. 3,621, 534 Dated November 23, 1971 nventor(5GEORGES D. DE TROYER It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

IN THE SPECIFICATION Column 2, line 53, change "each" to such Column 6,line 60, correct the spelling of "holder" line 64, correct the spellingof "bores" IN THE] CLAIMS Column 11, lines 36-37, correct the spellingof "threaded" Column 12, line 37, change "surfaces" to surface Signedand sealed this Sth day of April i92.

JRD 'f.FLETCHER, JR. ROBERT GOTTSCHLK U Attesting Officer' Commissioner*o1 Patents FORM 2o-1050 (1D-69) uscoMM-Dc eos'le Psv LLS4 GOVERNMENTPMNTONG OFFICE |969 0-366-.154

